// Copyright 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef NET_WEBSOCKETS_WEBSOCKET_DEFLATE_STREAM_H_
#define NET_WEBSOCKETS_WEBSOCKET_DEFLATE_STREAM_H_

#include <stddef.h>

#include <memory>
#include <string>
#include <vector>

#include "base/macros.h"
#include "net/base/completion_callback.h"
#include "net/base/net_export.h"
#include "net/websockets/websocket_deflater.h"
#include "net/websockets/websocket_frame.h"
#include "net/websockets/websocket_inflater.h"
#include "net/websockets/websocket_stream.h"

class GURL;

namespace net {

class WebSocketDeflateParameters;
class WebSocketDeflatePredictor;

// WebSocketDeflateStream is a WebSocketStream subclass.
// WebSocketDeflateStream is for permessage-deflate WebSocket extension[1].
//
// WebSocketDeflateStream::ReadFrames and WriteFrames may change frame
// boundary. In particular, if a control frame is placed in the middle of
// data message frames, the control frame can overtake data frames.
// Say there are frames df1, df2 and cf, df1 and df2 are frames of a
// data message and cf is a control message frame. cf may arrive first and
// data frames may follow cf.
// Note that message boundary will be preserved, i.e. if the last frame of
// a message m1 is read / written before the last frame of a message m2,
// WebSocketDeflateStream will respect the order.
//
// [1]: http://tools.ietf.org/html/draft-ietf-hybi-permessage-compression-12
class NET_EXPORT_PRIVATE WebSocketDeflateStream : public WebSocketStream {
public:
    WebSocketDeflateStream(std::unique_ptr<WebSocketStream> stream,
        const WebSocketDeflateParameters& params,
        std::unique_ptr<WebSocketDeflatePredictor> predictor);
    ~WebSocketDeflateStream() override;

    // WebSocketStream functions.
    int ReadFrames(std::vector<std::unique_ptr<WebSocketFrame>>* frames,
        const CompletionCallback& callback) override;
    int WriteFrames(std::vector<std::unique_ptr<WebSocketFrame>>* frames,
        const CompletionCallback& callback) override;
    void Close() override;
    std::string GetSubProtocol() const override;
    std::string GetExtensions() const override;

private:
    enum ReadingState {
        READING_COMPRESSED_MESSAGE,
        READING_UNCOMPRESSED_MESSAGE,
        NOT_READING,
    };

    enum WritingState {
        WRITING_COMPRESSED_MESSAGE,
        WRITING_UNCOMPRESSED_MESSAGE,
        WRITING_POSSIBLY_COMPRESSED_MESSAGE,
        NOT_WRITING,
    };

    // Handles asynchronous completion of ReadFrames() call on |stream_|.
    void OnReadComplete(std::vector<std::unique_ptr<WebSocketFrame>>* frames,
        const CompletionCallback& callback,
        int result);

    // This function deflates |frames| and stores the result to |frames| itself.
    int Deflate(std::vector<std::unique_ptr<WebSocketFrame>>* frames);
    void OnMessageStart(
        const std::vector<std::unique_ptr<WebSocketFrame>>& frames,
        size_t index);
    int AppendCompressedFrame(
        const WebSocketFrameHeader& header,
        std::vector<std::unique_ptr<WebSocketFrame>>* frames_to_write);
    int AppendPossiblyCompressedMessage(
        std::vector<std::unique_ptr<WebSocketFrame>>* frames,
        std::vector<std::unique_ptr<WebSocketFrame>>* frames_to_write);

    // This function inflates |frames| and stores the result to |frames| itself.
    int Inflate(std::vector<std::unique_ptr<WebSocketFrame>>* frames);

    int InflateAndReadIfNecessary(
        std::vector<std::unique_ptr<WebSocketFrame>>* frames,
        const CompletionCallback& callback);

    const std::unique_ptr<WebSocketStream> stream_;
    WebSocketDeflater deflater_;
    WebSocketInflater inflater_;
    ReadingState reading_state_;
    WritingState writing_state_;
    WebSocketFrameHeader::OpCode current_reading_opcode_;
    WebSocketFrameHeader::OpCode current_writing_opcode_;
    std::unique_ptr<WebSocketDeflatePredictor> predictor_;

    DISALLOW_COPY_AND_ASSIGN(WebSocketDeflateStream);
};

} // namespace net

#endif // NET_WEBSOCKETS_WEBSOCKET_DEFLATE_STREAM_H_
